Machining (lathe turning or milling) has been conventionally employed as a method of patterning or making grooves on the surface of a metallic rod.
However, the metallic rod usually has a curved portion which is enlarged when the curved portion is subjected to a heat treatment etc.
Furthermore, since the rod is not always perfectly circular in its cross section but it may be elliptical or eccentric, machining such rods, heavy rods and long rods, uniforming the depth of the grooves and processing the rod with high accuracy are difficult, which involves high cost.
The present invention has improved the drawback of the conventional processing method and is to provide a method of processing the rod capable of forming patterns of very shallow grooves on the surface of the rod etc. with ease and high accuracy.